Protoliths of the Napier Complex in Enderby Land, East Antarctica; an overview and implication for crustal formation of Archaean continents

Ishizuka, Hiroki

doi:10.2465/jmps.080328

Cited by 8 publications

(3 citation statements)

References 34 publications

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“…Although life may have appeared only a few hundred million years after Earth's accretion (e.g., Lopez-Garcia et al 2006), sedimentary rocks older than~3,850 Ma (Nutman et al 1996;Ishizuka 2008;Nutman et al 2010;O'Neil et al 2011;Mloszewska et al 2012), where biotic events are most likely to be imprinted, are uncommon on Earth. Yet, potential traces of life (e.g.…”

Section: The Setting For Early Lifementioning

confidence: 99%

Early life on land and the first terrestrial ecosystems

Beraldi-Campesi¹

2013

Ecol Process

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Terrestrial ecosystems have been largely regarded as plant-dominated land surfaces, with the earliest records appearing in the early Phanerozoic (<550 Ma). Yet the presence of biological components in pre-Phanerozoic rocks, in habitats as different as soils, peats, ponds, lakes, streams, and dune fields, implies a much earlier type of terrestrial ecosystems. Microbes were abundant by~3,500 Ma ago and surely adapted to live in subaerial conditions in coastal and inland environments, as they do today. This implies enormous capacities for rapid adaptations to changing conditions, which is supported by a suggestive fossil record. Yet, evidence of "terrestrial" microbes is rare and indirect in comparison with fossils from shallow or deeper marine environments, and its record has been largely overlooked. Consequently, the notion that microbial communities may have formed the earliest land ecosystems has not been widely accepted nor integrated into our general knowledge. Currently, an ample record of shallow marine and lacustrine biota in~3,500 Ma-old deposits, together with evidence of microbial colonization of coastal environments~3,450 Ma ago and indirect geochemical evidence that suggests biological activity in >3,400 Ma-old paleosols endorses the idea that life on land perhaps occurred in parallel with aquatic life back in the Paleoarchean. The rapid adaptations seen in modern terrestrial microbes, their outstanding tolerance to extreme and fluctuating conditions, their early and rapid diversification, and their old fossil record collectively suggest that they constituted the earliest terrestrial ecosystems, at least since the Neoarchean, further succeeding on land and forming a biomass-rich cover with mature soils where plant-dominated ecosystems later evolved. Understanding how life diversified and adapted to non-aquatic conditions from the actualistic and paleontological perspective is critical to understanding the impact of life on the Earth's systems over thousands of millions of years.

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Section: The Setting For Early Lifementioning

confidence: 99%

Early life on land and the first terrestrial ecosystems

Beraldi-Campesi¹

2013

Ecol Process

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“…1). Investigations since the 1960s by Australian, Russian and Japanese scientists have outlined a basic framework for the Archean geological history of the Napier Complex (summarized by Sheraton and others, 1987;Harley and Kelly, 2007;Ishizuka, 2008aIshizuka, , 2008band Hokada and others, 2008), which includes at least two high-grade metamorphic events: at ϳ2.8 Ga and ϳ2.5 Ga (Kelly and Harley, 2005). The complex comprises granitic, charnockitic and enderbitic gneisses, intercalated with lesser amounts of felsic and pelitic paragneisses, and minor proportions of mafic to ultramafic orthogneisses and meta-ironstones (Sheraton and others, 1987;Harley and Black, 1997;Hokada and others, 2004).…”

Section: Geological Settingmentioning

confidence: 99%

Changes in zircon chemistry during Archean UHT metamorphism in the Napier Complex, Antarctica

Kusiak¹,

Whitehouse²,

Wilde³

et al. 2013

American Journal of Science

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Zircons from two paragneisses (from Mount Sones and Dallwitz Nunatak) and one orthogneiss (from Gage Ridge) in the Tula Mountains, Napier Complex (East Antarctica) were analyzed for U-Pb age, oxygen isotopes, REEs and by scanning ion imaging. A large number of zircons from all samples are reversely discordant. Mount Sones zircons show an age range from 3.0 Ga to 2.5 Ga and underwent high-grade metamorphism at both ϳ2.8 Ga and 2.5 Ga. Zircons from Dallwitz Nunatak record detrital ages between 3.5 Ga and 2.5 Ga. Zircons from Gage Ridge record multiple age groups, with concordant data between 3.6 Ga and 3.3 Ga and reversely discordant data that form a discrete ϳ3.8 Ga population. All of the grains show evidence of Pb mobility during metamorphism. Ion imaging of zircons reveals Y and U zonation, characteristic of magmatic zircon, together with a micro-scale patchy distribution of 206 Pb and 207 Pb that does not correspond to either growth zonation or crystal imperfections. Some of these patches yield 207 Pb/ 206 Pb ages >4 Ga, whereas others yield ages younger than the magmatic crystallization age. Reversely discordant data are the result of ancient Pb mobilization, which is independent of the degree of metamictisation, oxygen isotope and REE content of the zircons. This mobilization can result in spurious ages and was most likely caused by polymetamorphism under anhydrous conditions; that is two high-grade events; one poorly defined at ϳ2.8 Ga and the other ultra-high temperature (UHT) metamorphism at 2.5 Ga.

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“…López-García et al, 2006), el registro sedimentario más antiguo (donde los eventos bióticos son más propensos a ser conservados) no sobrepasa los ~3850 Ma (Nutman et al, 1996;Ishizuka, 2008;Nutman et al, 2010;O'Neil et al, 2011;Mloszewska et al, 2012). Y aún en este registro tan antiguo, potenciales biofirmas (carbonatos precipitados biogénicamente) pudieran estar presentes (Nutman et al, 2010), lo cual sugiere que la biósfera podría ser varios millones de años más antigua que los estromatolitos y microfósiles más antiguos conocidos (~3500 Ma).…”

Section: El Escenario De La Vida Tempranaunclassified

La vida temprana en la Tierra y los primeros ecosistemas terrestres

Beraldi-Campesi¹

2014

BSGM

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La vida temprana en la Tierra y los primeros ecosistemas terrestres 65 ResumenLos ecosistemas terrestres han sido considerados tradicionalmente como superficies dominadas por plantas, cuyos primeros registros datan del Fanerozoico temprano (< 550 Ma/millones de años). Sin embargo, la presencia de componentes biológicos mucho más antiguos que las plantas en hábitats tan distintos como suelos, turberas, estanques, lagos, arroyos y dunas, sugiere que los ecosistemas terrestres comenzaron a existir en la Tierra hace al menos 2700 Ma. Los microbios fueron abundantes hace ~3500 Ma y sin duda se adaptaron a vivir en condiciones subaéreas, en entornos intermareales y en zonas áridas y semiáridas, como lo hacen actualmente los microbios terrestres, y que tienen una enorme y rápida capacidad de adaptación a condiciones cambiantes. Todo ello está respaldado por el registro fósil. No obstante, esta evidencia es inusual e indirecta en comparación con fósiles de ambientes marinos, superficiales o profundos, y su registro ha sido poco atendido. En consecuencia, la noción de que fueron comunidades microbianas las que formaron los primeros ecosistemas terrestres no ha sido ampliamente difundido ni incorporado conceptualmente en la sociedad. Hoy conocemos un amplio registro fósil de biota marina somera y lacustre a partir de los ~3500 Ma, así como microbios colonizando ambientes costeros desde hace ~3450 Ma y evidencia indirecta de actividad biológica en paleosuelos de > 3400 Ma de edad. El tipo de ambientes, de donde proviene esta evidencia, sugiere que la vida terrestre se produjo casi en paralelo con la vida acuática en el Arqueano. Las rápidas adaptaciones observadas en microbios actuales, su excepcional tolerancia a condiciones extremas y fluctuantes, su rápida y temprana diversificación y su antiguo registro fósil, indican que los primeros ecosistemas terrestres fueron exclusivamente microbianos. Es factible que los microbios contribuyeran en la formación de los primeros suelos donde las plantas se desarrollaron más tarde. Comprender cómo la vida se diversificó y adaptó a las condiciones terrestres es fundamental para entender su impacto en los sistemas terrestres durante millones de años. Beraldi-Campesi 66 661. Introducción Definición de terrestreLos ambientes terrestres seguramente han existido a través de toda la historia geológica de la Tierra a menos que su superficie estuviera permanentemente bajo el agua, lo cual no es aceptablemente realista. La definición de 'terrestre' no es tan trivial como parece. Aunque aquí se define como un ambiente 'no acuático', la distinción entre lo marino y lo terrestre atraviesa un amplio espectro de ambientes transicionales, donde lo acuático y lo no-acuático evolucionan y superponen en el tiempo. Comúnmente se entiende que un entorno terrestre (sobre el nivel del mar), puede incluir ambientes acuáticos (lagos cubiertos o no de hielo, lagunas y humedales, turberas, ríos y arroyos, campos geotérmicos) y no-acuáticos (especialmente zonas con poca lluvia). Estos hábitats pueden experimen...

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Protoliths of the Napier Complex in Enderby Land, East Antarctica; an overview and implication for crustal formation of Archaean continents

Cited by 8 publications

References 34 publications

Early life on land and the first terrestrial ecosystems

Early life on land and the first terrestrial ecosystems

Changes in zircon chemistry during Archean UHT metamorphism in the Napier Complex, Antarctica

La vida temprana en la Tierra y los primeros ecosistemas terrestres

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